Short pulse keying attachment



Nov. 27, 1962 L. R. PADBERG, JR., ETAL 3,066,273

SHORT PULSE KEYING ATTACHMENT 2 Sheets-Sheet 1 Filed May 25, 1956 I INDICATOR CONSOLE l I l I l l I R. mm u Wm. A. m 2 -55. 35. R DRYP 10 a 444. r PPHD T g RDC A I F wnwm LFJM v! a DELAY TIME -PULSE TIME RELAY con. mos

ACTUATION SIGNAL RELAY CONTACTS OUTPUT OF DELAY- OUTPUT OF PULSE Q2) OSCILLATOR emu OSCILLATOR OUTPUT Nov. 27, 1962 R. PADBERG, JR., ETAL 3,066,278

SHORT PULSE KEYING ATTACHMENT Filed May 25, 1956 2 Sheets-Sheet 2 DELAY PULSE PULSE WIDTH KEYER Ell TO AMPLIFIER IN V EN TOR. LOU/S R PADBERG, JR

FR PA RK I? M52 9. HA YE M LTON DJAPINEAU BY 6 a ATTORNEYS 3,ihi6,278 Patented Nov. 27, 1962.

3,066,278 SHORT PULSE KEYKNG ATTACHMENT Louis R. Padberg, Jr., Fred 1).. Parker, John C. Hayes,

and Milton D. Papineau, all of San Diego, (Ialih, assignors to the United States of America as represented by the Secretary of the Navy Filed May 25, 1956, Ser. No. 587,433 7 Claims. (Cl. 340-3) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the pay ment of any royalties thereon or therefor.

This invention relates to pulse transmission and more particularly to that modification of existing sonar apparatus which adapts such apparatus for short pulse operation.

It has been definitely established that under certain oceanographic conditions superior tracking results may be obtained by being able to utilize pulses much shorter than are provided in the conventional equipment. It has also been shown that very short pulses help in detecting small objects. In areas of high reverberation it is sometimes possible to track a submarine with short pulses while the conventional lengths cause the trace to be smeared together and recognition becomes extremely difficult or impossible.

In several types of conventional sonar equipments employing pulse techniques, the Width or duration of the pulse projected by a projecting transducer is determined solely by the time that a signal generator is coupled with the transducer. This coupling is effected by the closing of a keying and transfer relay which has the coil thereof energized by a keying pulse of the predetermined duration. While, in this arrangement the pulse length is adjustable, it is not possible to provide a pulse length of five milliseconds or less because of the physical characteristics of the relay. The inertia of the relay contacts, the variation in spring tension due to age and difierences in production, and the resilient bounce of the. contacts all contribute to poor shape of shorter pulses. The present invention comprises an attachment which does not interfere with the normal operation of the existing equipment and which may be switched into operation when use of a shorter pulse is indicated. The relay is allowed to close for the duration for which it is designed but there is substituted for the energization of the signal generator which is effected by the relay, a preformed short pulse which is synchronized from the key-v ing pulse. When the relay is first closed, there is a tendency for the contacts to bounce, thus causing undesired transients to appear in the output pulse. In order to eliminate this effect the preformed short pulse is delayed relative to the leading edge of the keying pulse (the initiation of the closing of the relay contacts) whereby the relay contacts have stabilized before the signal generator is energized and the latter is de-encrgized before the contacts open.

It is an object of this invention to produce short pulses of good wave shape.

A further object of this invention is the adaptation of existing long pulse sonar equipment to short pulse oper-- ation.

Still another object of this invention is the elimination of pulse shape distortion caused by a keying and transfer relay.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 comprises a block diagram of the short pulse modification of a conventional sonar equipment;

FIG. 2 is a synchrograph of waveforms appearing in the apparatus of FIG. 1; and

FIG. 3 is a schematic circuit diagram of part of the apparatus of FIG. 1.

In the drawings like numerals refer to like parts.

For convenience, and as an exemplary embodiment only, the present invention is disclosed in combination with certain connected components of the driver of a sonar equipment konwn as QGB which is described in detail in the five volumes of Search Sonar Maintenance. Training Program, NavPers 91910, published by the Bureau of Naval Personnel, and particularly in Section ll, Topics 2A through 2D of Volume 1, and Section V, Topic 2 of Volume 3.

As shown in FIG. 1 the QGB sonar includes a keyer tube V5194 which, under control of a pulse repetition rate multivibrator (not shown) passes a current through coil it) of keying and transfer relay K to close contacts l2 and 14 thereof for the duration of conduction of tube V5104. Tube V101, connected as an oscillator 15 has the output thereof coupled to the projecting transducer 16 through power amplifier and output transformer 18 and contacts 14 of the relay. The oscillator, normally cut off by a bias supplied through resistor 20 from a source of negative voltage, is energized by the closing of contacts 12 which raises the grid of tube V101 to ground potential. The structure described above produces a projected pulse of compressional wave energy having a width determined by the closure time of the transfer relay-K105 which in-eifect comprises a long pulse device which cou+ ples the output of the oscillator or signal generator-15 with the transducer and simultaneously energizes theoscillator. The width of the keying pulse produced by tube VSHM is adjustable but has a minimum duration determined by the physical characteristics of transfer relay consistent with uniform operation and good pulse shape.

In order to obviate the limits on pulse width imposed by the relay there is provided a pulse delay multivibrator 22 triggered by the keyer tube to produce a delayed signal which triggers the pulse width multivibrator 24. .The latter produces a pulse of the desired short length which is applied to the grid of tube V101 through resistor 26,. radio frequency choke coil 28 and cathodeflfollower keyer 30 when relay 32 is energized by the closing of switch S].- which is conveniently mounted on the control console :of

the equipment.

With switch S1 open, in normal position, relay 32 'isinot energized, keyer 30 and multivibrators 22, 24 are'disconnected from the oscillator, and contacts 12 of relayKlUfiS are coupled to the oscillator whereby normal long pulse operation of the equipment may be'elfected as in the complete absence of the short pulse attachment.

Closing of manual switch S1 supplies-a current from a; suitable voltage source 34 to the coil of relay 32 to .disconnect the long pulse forming means from the oscillator input and simultaneously couple the short pulse appara tus to tube V101. a

The variable width keying pulse B (FIG. 2), initiated at time t causes the relay contacts to make initial-con tact at slightly delayed time t due to inertia of the con-. tacts. The bounce time of the contacts, indicated-by the shaded portion of curve A, is obviated in short pulse operation by causing the trailing edge of delay pulse C (trig-. gered at time t by the leading edge of pulse B) to occur at a time t after the bounce time of the contacts. Thetrailing edge of pulse C triggers the short pulse D (t t formed by the pulse width multivibrator to effect at the grid and plate of the oscillator the wave-forms E and F respectively.

It will be seen that the relay K105 is allowed to close for the duration for which it is designed and the preformed short pulse is timed to start after stabilization of the relay contacts and is terminated before time 2 when the contacts open whereby the effect of the keying and transfer relay upon the pulse length and shape is entirely eliminated. This improved alternative operation is achieved with slight modification of the existing equipment and without disturbing its ability to function in the manner for which it was designed.

As shown in FIG. 3, the delay is provided by a monostable cathode coupled multivibrator 22 comprising a dual triode 36 which is triggered to unstable condition by the negative going portion of the keying pulse B applied through coupling capacitor 35. Upon return to stable condition after a time determined by the discharge time of capacitor 38 the negative going trigger (at time t drives into non-stable condition the pulse width multivibrator 24 which comprises a dual triode 40 connected as a cathode coupled monostable multivibrator. The latter remains in unstable condition for a time t t determined by the discharge time of plate to grid coupling capacitor 42 to produce pulse D. The keyer 30, a pair of triodes 44 connected to in parallel as cathode followers and normally cut off by a bias supplied through resistor 46 from a source of negative potential, is caused to conduct by the application of the positive pulse D to the control grids thereof. The increase in cathode potential of tube 44, during conduction, is fed through relay 32, coil- 28 and resistor 26 to raise the grid of tube V101 which is thus energized and caused to produce the short pulse F of the predetermined length and at the proper time relative to actuation of the keying and transfer relay K105.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1 In a combination long pulse-short pulse echo ranging system, keying means for producing a long pulse signal, a transducer, a first switching means adapted to be connected between said long pulse signal producing means. and said transducer, a pulse delay means energized by the long pulse signal from said long pulse producing means for providing a signal whose pulse is delayed a predetermined time interval with respect to the initial generation of said long pulse, means responsive to said delayed signal for producing a short pulse signal simultaneously with the production of said long pulse, a second switching means connected to said first switching means and adapted to be selectively interposed between said long pulse signal producing means and said short pulse signal producing means, whereby said transducer is driven by a long pulse signal when said second switching means is connected to said long pulse signal producing means and said transducer is driven by a short pulse signal when said second switching means is connected to said short pulse signal producing means.

2. A device as set forth in claim 1' wherein said keying means for producing a long pulse signal includes a triode tube responsive to the pulse of a repetition rate trigger, a positive voltage source, a transfer relay including a solenoid and closable switch contacts actuatable thereby, said solenoid being electrically connected between said tube and said positive voltage source in such manner that, when said tube conducts, said solenoid is energized and said switch contacts close to produce a long pulse signal thereat.

3.. In a combination long pulse-short pulse echo ranging system, a keyer tube having an input responsive to an electrical pulse and an output including an amplified long pulse, a first relay means comprising a solenoid for actuating a first switch and a second switch simultaneously, said solenoid being connected to the output of said keyer tube in such manner as to close said first and second switches during conduction thereof, a second relay having a solenoid adapted to be energized from a power source, a first contact connected to ground through the second switch of said first relay, a second contact, a throw member alternately engageable with said first and second contacts when said second relay solenoid is deenergized and energized respectively, an oscillator having an input and an output, a reactance means, an impedance means connected in series with said reactance means, said oscillator input being electrically coupled to the first contact of said second relay through said series con nected reactance and impedance means, a transducer connected to the output of said oscillator means through the first switch of said first relay so that said transducer is energized by a long pulse when said first relay is energized and said second relay is de-energized, a pulse delay means connected to the output of said keyer tube for producing an output signal subsequent to the attenuation of stray transients broadcast during the closing of said first relay switches, a multivibrator responsive to said delay means output signal for producing a pulse which is short in duration compared to the aforesaid long keyer tube output pulse, cathode follower means interconnecting said multivibrator and said second contact of said second relay for efiecting circuit isolation therebetween, and manually operable means electrically connected between said second relay solenoid and the aforesaid power source for energizing and de-energizing said second relay solenoid, whereby the short pulse produced by said multivibrator actuates said transducer when said second relay solenoid is energized, without being modulated by transient signals caused by the closing of said first relay switches, and whereby the long pulse produced by said keyer tube actuates said transducer when said second relay solenoid is de-energized.

4. In an echo ranging system, a keyer, a relay coupled to the output of said keyer having a pair of switches adapted to be closed thereby, an oscillator, a transducer, said oscillator and said transducer being adapted for in terconnection by one of said pair of relay switches, a pulse delay means coupled to the output of said keyer, a pulse width means connected to the output of said pulse delay means, a cathode follower coupled to the output of said pulse width means, and selector switch means connected to the input of said oscillator for selectively connecting same to the output of said cathode follower and ground as desired.

5. A short pulse keying attachment for a long pulse echo ranging system comprising in combination, means for generating a long pulse signal, means connected to said generating means for producing a delayed short pulse signal in response to said long pulse signal and simultaneously therewith, transducer means adapted for being selectively connected to said long pulse signal generating means and said short pulse signal producing means for energization by said long and short pulse signals, respectively, and means connected between the input of said transducer means and the outputs of said long pulse signal generating means and said short pulse signal generating means for selectively supplying thereto oscillatory signals of higher frequency than the frequency of said short pulse Signals for a period proportional to the widths thereof respectively.

6. A short pulse keying attachment adapted to be actuated by the long pulse signal of a long pulse echo ranging system consisting of a transducer, an oscillator, means adapted to connect the output of said oscillator to said transducer in response to a long pulse signal received from said echo ranging system, means responsive to the long pulse signal received from said echo ranging system for simultaneously generating therewith a short pulse signal delayed a predetermined period of time with respect to initial reception thereof, and means for connecting and disconnecting the input of said oscillator to the output of said delayed short pulse signal generating means for respective actuation and deactuation thereby at predetermined times after the output thereof is connected to said transducer.

7. A short pulse keying attachment adapted for converting a relatively long echo-ranging signal containing adverse operational noise characteristics into a comparatively short echo-ranging signal substantially devoid of adverse operational noise characteristics comprising in combination, means for generating a long pulse signal, means connected to the output of said generating means for producing a delayed pulse signal in response to said long pulse signal, means coupled to said delayed pulse signal producing means for producing a pulse signal of predetermined width which is short compared to the width of the aforesaid long pulse signal, an oscillator, a transducer adapted to be connected to the output of said oscillator, means coupled to the output of said long pulse 6 signal generating means for timely connecting said transducer to the output of said oscillator, and means connected to the input of said oscillator for selectively connecting same to the outputs of said long pulse generating means and said short pulse producing means as desired.

References Cited in the file of this patent UNITED STATES PATENTS 

